Stress and strain intensity factors within angle area of the boundary

2018 ◽

Vol 193 ◽

pp. 03029

Author(s):

Lyudmila Frishter

Keyword(s):

Strain State ◽

Engineering Practice ◽

Stress And Strain ◽

Strain Intensity ◽

Intensity Factors ◽

Stress Strain ◽

Elasticity Theory Problem ◽

Limit Values ◽

Stress Strain State ◽

Irregular Point

The stress-strain state of structures in areas with corner cut-outs and cuts of boundaries features the occurrence of areas of stress concentration and requires assessment of strength and reliability of facilities, which is a relevant task in engineering practice. Theoretical analysis of stress-strain state (SSS) of corner cut-outs zones of the area boundary is reduced to the study of singular solutions of the elasticity theory problem with exponential features. At that, the concept of stress or strain concentration in an irregular point of the area boundary is meaningless. This paper considers the stress-strain state in the vicinity of the top of the corner cut-out of the flat area boundary, which is recorded using the intensity factors as limit values of stresses and strains. We give two approaches for obtaining the limit values for stress and strain in the vicinity of an irregular point of the plane area boundary using the stress intensity factors and the strain intensity factors. The stress-strain state in the corner cut-outs zone of structures and buildings boundary recorded in the form of limit values of stresses and strains may further be used to determine and record the influence of changing the factors of intensity of stresses and strains on SSS of structures, which is a separate task of solid mechanics. The difference in the expressions of stresses and displacements obtained for limit values of stresses and strains determines practical significance of the work when carrying out experiments and at determination of critical values of stresses and strains.

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Stress and Strain Intensity Factors of the Corner Area of the Structure Boundary

Materials Science Forum ◽

10.4028/www.scientific.net/msf.931.30 ◽

2018 ◽

Vol 931 ◽

pp. 30-35

Author(s):

Lyudmila U. Frishter

Keyword(s):

Strain State ◽

Practical Significance ◽

Engineering Practice ◽

Stress And Strain ◽

Building Structures ◽

Strain Intensity ◽

Intensity Factors ◽

Plane Region ◽

The Difference ◽

Irregular Point

The Stress and strain state of building structures in zones with bird's mouths and cuts of the boundary is characterized by stress concentration zones emergence and requires an evaluation of strength and reliability of objects, which is the engineering practice actual task. Theoretical analysis of stress and strain state of bird's mouth areas of the region boundary is confined to the study of singular solutions of the elasticity problem with power singularities. In this case, the concept of stress or strain concentration at an irregular point of the region boundary becomes meaningless. In the present article, stress and strain state is considered in the neighborhood of the bird's mouth vertex of the boundary of a plane region, which is written with the help of the intensity factors. Two approaches are given to obtaining the expressions for displacements, stresses in the neighborhoods of an irregular point of the boundary of a plane region by means of stress intensity factors and strain intensity factors. The difference in the expressions for stresses and displacements obtained for the limiting values of stresses and strains determines the practical significance of the work during the experiments and the determination of the critical values of stresses and strains.

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Thermal Fatigue Evaluation Model of a Microelectronic Chip in Terms of Interfacial Singularity

Journal of Electronic Packaging ◽

10.1115/1.4045255 ◽

2019 ◽

Vol 142 (1) ◽

Author(s):

Xiaoguang Huang ◽

Zhiqiang Wang

Keyword(s):

Thermal Fatigue ◽

Evaluation Method ◽

Evaluation Model ◽

Thermomechanical Properties ◽

Fatigue Tests ◽

Strain Intensity ◽

Intensity Factors ◽

Singular Stress ◽

Stress Strain ◽

Fatigue Evaluation

Abstract Thermal fatigue failure of microelectronic chip often initiates from the interface between solder and substrate, and the service life of the chip is largely dependent on the singular stress–strain at this interface. To provide a reasonable life evaluation method, three thermal fatigue evaluation models, including strain-based and stress–strain based, have been established in terms of the interfacial singular fields. Thermal fatigue lives of different chips under different thermal cycles are obtained by thermal fatigue tests, and the stress and strain intensity factors and singular orders at the solder/substrate interface are computed at the same conditions, to determine the material constants in the established models. The thermal fatigue lives predicted are in acceptable agreement with the experimental results. What is more, the application of these thermal fatigue models demonstrates a fact that the thermal fatigue of the microelectronic chips can be evaluated uniformly no matter what the shapes, dimensions of the chip, and the thermomechanical properties of the solders are, as long as the relevant stress–strain intensity factors and singular orders are obtained.

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Numerical estimation of strain intensity factors at the tip of a rigid line inclusion embedded in a finite matrix

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2016.12.021 ◽

2017 ◽

Vol 172 ◽

pp. 215-230 ◽

Cited By ~ 4

Author(s):

Prataprao Patil ◽

S.N. Khaderi ◽

M. Ramji

Keyword(s):

Strain Intensity ◽

Numerical Estimation ◽

Intensity Factors ◽

Rigid Line Inclusion ◽

Finite Matrix ◽

Rigid Line ◽

Line Inclusion

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Numerical evaluation of the interaction of rigid line inclusions using strain intensity factors

International Journal of Mechanical Sciences ◽

10.1016/j.ijmecsci.2019.01.017 ◽

2019 ◽

Vol 153-154 ◽

pp. 10-20 ◽

Cited By ~ 5

Author(s):

T.M. Jobin ◽

M. Ramji ◽

S.N. Khaderi

Keyword(s):

Numerical Evaluation ◽

Strain Intensity ◽

Intensity Factors ◽

Rigid Line

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Numerical Stress Intensity Factors Determination for Fabrication Defects in Coronary Stents

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.488-489.718 ◽

2011 ◽

Vol 488-489 ◽

pp. 718-721 ◽

Cited By ~ 1

Author(s):

Cristian Sorin Nes ◽

Angelica Enkelhardt ◽

Nicolae Faur ◽

Adrian Birlan

Keyword(s):

Stress Intensity ◽

Crack Initiation ◽

Stress Intensity Factors ◽

Coronary Stents ◽

Large Strains ◽

Stress And Strain ◽

Crack Initiation And Propagation ◽

Intensity Factors ◽

Hexahedral Elements ◽

Initiation And Propagation

Objectives: Numerical stress intensity factors (SIFs) computation for several fabrication defect geometries in coronary stents. XFEM crack initiation and propagation was also performed. Methods: The model represents a self-expandable coronary stent, made from a shape memory alloy (L-605). Several flaw shapes are considered. The analysis was performed using the ABAQUS code. The loads and boundary conditions simulate the interaction between the blood vessels and stents, immediately after the angioplasty was performed. The mesh contains 3d stress hexahedral elements. For global stress and strain distributions, the model of a complete stent was used. For crack propagation analysis and SIF determination, the model represented a single segment of the stent. The stress intensity factors were computed using the contour integral method. Results and conclusions: The stress and strain fields highlight the negative effects of crack initiation and propagation on the residual life of the stent. Furthermore, by compromising the structural integrity of the stent, large strains may occur, thus increasing the risk of restenosis and further stenosis-related complications. The stress intensity factors indicate the most dangerous locations for the flaws (cracks), as well as the most dangerous geometries.

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Stress-Intensity Factors for Arbitrarily Oriented Cracks in Shallow Shells

Journal of Applied Mechanics ◽

10.1115/1.3424215 ◽

1978 ◽

Vol 45 (1) ◽

pp. 135-141 ◽

Cited By ~ 7

Author(s):

J. G. Simmonds ◽

M. R. Bradley ◽

J. W. Nicholson

Keyword(s):

Stress Intensity ◽

Stress Intensity Factors ◽

Fourier Transforms ◽

Singular Integral Equations ◽

Stress And Strain ◽

Crack Orientation ◽

Intensity Factors ◽

Shallow Shells ◽

Short Cracks ◽

Line Of Curvature

The equations describing the stress and strain fields in an elastically isotropic shallow shell containing a crack are reduced, via Fourier transforms, to four coupled singular integral equations plus side conditions. A perturbation solution, useful for relatively short cracks, is constructed for a pressurized shell of revolution containing a stress-free crack that makes an arbitrary angle with a line of curvature of the midsurface. First-order corrections due to curvature and crack orientation of the mode I (opening) and mode II (shearing) stress-intensity factors for a plate are computed analytically.

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